Grinding machine

ABSTRACT

The present invention comprises a grinding machine ( 1 ) for grinding a surface of a workpiece ( 6 ), wherein the grinding machine ( 1 ) has
         at least one abrasive holder ( 2 ), on which at least one abrasive ( 4 ) is arranged, and   at least one drive device for moving the abrasive holder ( 2 ),
 
wherein the drive device has at least one drive shaft ( 12 ), on which an eccentric element ( 16 ) is arranged and which can be rotated about an axis of rotation ( 18 ), wherein the eccentric element ( 16 ) is arranged on the abrasive holder ( 2 ) at a distance from the axis of rotation ( 18 ), wherein it is possible to adjust the distance.

The invention relates to a grinding machine for grinding a surface of a workpiece, wherein the grinding machine has at least one abrasive holder, on which at least one abrasive is arranged, and at least one drive device for moving the abrasive holder, wherein the drive device has at least one drive shaft, on which an eccentric element is arranged and which can be rotated about an axis of rotation, wherein the eccentric element is arranged on the abrasive holder at a distance from the axis of rotation.

Such a grinding machine is known, for example, from DE 102 039 191 A1. Consequently, the eccentric element connects the at least one drive shaft to the abrasive holder such that the fastening of the eccentric element on the abrasive holder is spaced apart from the axis of rotation, which constitutes in particular an extension of the drive shaft along its longitudinal direction. If, then, the drive shaft is rotated, for example an electric motor being provided for this purpose, it is also the case that the eccentric element is made to rotate, which results in an oscillating movement of the abrasive holder and thus of the abrasive.

Such abrasives can be used in dependence on the pressure-exerting element used, and on the oscillating speed in relation to the advancement speed of a tool piece to be ground, so as to achieve a particularly homogeneous grinding result, in which there are therefore hardly any grinding marks evident, if any at all, or to introduce in a specific manner into the surface certain kinds of grinding mark, which can be increasingly used as design elements.

The invention is based on the object of further developing a grinding machine according to the preamble of Claim 1 such that a relatively large variety of grinding patterns can be introduced into the surface and the same abrasive can be used on different surfaces of the workpiece to be ground.

The invention achieves the set object by way of a grinding rail according to the preamble of Claim 1, which is distinguished in that it is possible to adjust the distance. The distance, once again, denotes the distance between the axis of rotation of the drive shaft and the point at which the eccentric element is arranged on the abrasive holder. If the distance can vary, this means that it is likewise possible to adjust the “displacement”, that is to say the maximum movement of the abrasive holder and thus of the abrasive on account of the oscillating movement which is caused by the rotation of the drive shaft. One result of this is that it is possible for different grinding patterns, which differ by way of different maximum movements and amplitudes of said oscillating movement, to be introduced into the surface.

Such an alteration in the grinding patterns was not possible to achieve using prior-art grinding machines. Prior-art machines were able to vary the form of the grinding patterns introduced only via a combination of rotational speed of the drive axis and/or advancement speed of the workpiece. The advancement speed of the workpiece, however, is often limited by the grinding effect to be achieved, that is to say the quantity of material which is to be removed. It is often not possible to increase the advancement speed in accordance with the design requirements, since, in the case of an increased advancement speed, it is often the case that the workpiece no longer comes into contact with the abrasive for a period sufficient to achieve the desired grinding result.

This problem is addressed by the configuration of the grinding machine according to the invention.

It is advantageously possible to adjust the length of the eccentric element. In this case, it is a particularly straightforward matter to adjust the movement amplitude of the abrasive holder, said amplitude being caused by the movement of the drive shaft. In a particularly straightforward configuration, the eccentric element has two sub-elements which are arranged on one another and can be fixed on one another for example at different positions. It is thus possible, for example, for the two sub-elements each to have a plurality of bores or apertures which can be made to coincide different positions of the two sub-elements relative to one another, wherein it is then possible for fastening elements, for example screws, to be guided through the bores or apertures and for the two sub-elements to be arranged on one another in this way. In order to alter the length of the eccentric element, said length being of decisive importance for the distance between the axis of rotation, the drive shaft and the point at which the eccentric element is arranged on the abrasive holder, all that is then required is for the fastening elements, for examples the screws, to be released and for the different bores or apertures of the two sub-elements to be made to coincide while the two sub-elements are in a different orientation relative to one another. This also alters the effective length of the eccentric element and thus the “displacement” of the oscillating grinding movement caused by the rotation of the drive shaft.

As an alternative to this, it is also possible for one of the sub-elements to have a groove with, for example, one or more undercuts. The other sub-element advantageously has a correspondingly shaped element, which engages in said grooves and is arranged in a longitudinally displaceable manner in the groove. It is possible here for the shaped element to be secured in different positions relative to the groove. This is advantageously done via clamping elements, and therefore the shaped element can be fastened, and locked, in the groove at more or less any desired position. This makes it possible to adjust the length of the eccentric element in a stepless manner.

As an alternative, or in addition, the eccentric element can advantageously be arranged in a releasable manner on the drive shaft. In addition, it can preferably be arranged in different positions on a drive shaft. As an alternative, or in addition, to the above described embodiment, in which the length of the eccentric element is altered, it is also possible to alter the position at which the eccentric element is arranged on the drive shaft. This also makes it possible to alter a distance between the point at which the eccentric element is arranged on the abrasive holder and the axis of rotation.

Advantageously arranged on the eccentric element and on the drive shaft are mutually corresponding form-fitting elements, by means of which the eccentric element can be arranged at least also in a form-fitting manner on the drive shaft. The form-fitting elements on the drive shaft here are arranged advantageously, but not necessarily, on the end side of the same.

In order to provide here for different positionings of the eccentric element on the drive shaft, the eccentric element advantageously has arranged on it a plurality of form-fitting elements which correspond to the form-fitting element on the drive shaft. The respective form-fitting elements together can form, for example, a kind of snap-fit closure, in the case of which for example a form-fitting element on the drive shaft snap-fits into a form-fitting element provided therefor on the eccentric element. This can take place, for example, in the manner of a snap fastener. It is possible here for the eccentric element to have a plurality of form-fitting elements which can each interact with the form-fitting element of the drive shaft. The selection of the form-fitting element which is actually brought into engagement with the form-fitting element on the drive shaft makes it possible to adjust the position of the eccentric element on the drive shaft and thus also the distance between the position at which the eccentric element is arranged on the abrasive holder and the axis of rotation.

As an alternative, or in addition, it is advantageously the case that at least one of the form-fitting elements is a guide track, in or on which another of the form-fitting elements is arranged in a displaceable manner. Here too, it is recommended, on account of the amount of installation space present, for the guide track, which may be, for example, a groove advantageously with at least one undercut, to be arranged on the eccentric element. The guide track may also be a, for example, elongate protrusion, for example a rail, which has at least one undercut in which a correspondingly shaped form-fitting element engages.

The form-fitting element which can be displaced in or on the guide track can advantageously be arrested, in particular clamped firmly, at different positions in the guide track. This makes it possible to adjust the variable distance in a stepless manner.

In a preferred configuration, the drive device has at least two drive shafts, on each of which an eccentric element is arranged. The eccentric elements are advantageously identical for the different drive shafts, and it is therefore possible to adjust the respective distance for each of the drive shafts. The adjustments take place advantageously in parallel.

The grinding machine advantageously has at least one pressure-exerting element, by means of which at least part of the abrasive can be subjected to pressure, wherein the pressure-exerting element can be moved relative to the abrasive. This makes it possible for additional grinding marks and grinding patterns to be introduced into the surface to be ground. For this purpose, it is advantageous if the pressure-exerting element has a surface which has a structure, which may be for example in the form of elevations and/or depressions. It is possible for these to be in the form of strips or zigzags, or to be of irregular form, and to be arranged in specific patterns or at random. The structure-containing surface of the pressure-exerting element is advantageously directed toward the abrasive.

An exemplary embodiment of the present invention will be explained in more detail hereinbelow with the aid of the accompanying drawings, in which:

FIG. 1—shows the schematic illustration of a grinding machine according to a first exemplary embodiment of the present invention, and

FIG. 2—shows detail-form illustrations of a drive shaft and an eccentric element in different positions and views.

FIG. 1 shows the schematic illustration of a grinding machine 1 according to a first exemplary embodiment of the present invention. It has an abrasive holder 2, on which an abrasive 4 is arranged. A workpiece 6 is moved along the advancement direction V by a transporting device (not shown) and comes into contact with the abrasive 4. A motor 10, which is part of a drive device, is located on a machine frame 8, of which, for reasons of clarity, only part is shown.

In the exemplary embodiment shown, the grinding machine 1 has two drive shafts 12, which are driven by the motor 10 in each case via power-transmission elements 14. An eccentric element 16 is arranged on each of the drive shafts 12 and is connected, in turn, to the abrasive holder 2. If, then, the respective drive shaft 12 is made to rotate to rotate about its longitudinal axis, which also serves as the axis of rotation 18, via the motor 10, it is, of course, also the case that the eccentric element 16 rotates, in which case the abrasive holder 2 and thus also the abrasive 4 are made to oscillate.

In the exemplary embodiment shown, the grinding machine 1 has a pressure-exerting element 20, which in the exemplary embodiment shown can be moved along the double arrow 24 via a movement mechanism 22, which is likewise configured in the form of a motor, preferably in the form of an electric motor. A structure is preferably located on a surface 26 of the pressure-exerting element 20, said surface being directed toward the abrasive 4.

In the case of a grinding machine 1 according to the invention, it is possible to adjust a distance between a position 28, at which the eccentric element 16 comes into contact with the abrasive holder 2, and the axis of rotation 18.

FIG. 2 shows, schematically, different sectional illustrations, from different perspectives, of a transition region between the drive shaft 12 and the eccentric element 16. We will look first of all at the two illustrations on the left-hand side of FIG. 2. The bottom one of these two illustrations shows a schematic sectional illustration through the drive shaft 12 in a direction perpendicular to the axis of rotation 18. The drive shaft 12 is illustrated as the smaller of the two circles. The larger of the two circles forms the schematic plan view of part of the eccentric element 16. It is possible to see a guide track 30, which is designed in the form of a projecting rail. This is shown, for example, in the top right-hand-side illustration, which shows a section in a direction parallel to the axis of rotation 18. It is possible to see the T-shaped configuration of the guide track 30, which has two undercuts 32, in each of which engages the form-fitting element 34 in the drive shaft 12. Fastening elements 36, which may be designed, for example, in the form of screws, can be used to secure the form-fitting element 34 on the guide track 30 and thus the drive shaft 12 on the eccentric element 16. The top left-hand-side illustration in FIG. 2 shows the sectional illustration in a direction parallel to the axis of rotation 18, albeit offset through 90° in relation to the illustration at the top right. It is possible to see the two fastening elements 36, an undercut 32 and the form-fitting element 34, which engages in said undercut.

The two illustrations in the center correspond to the two illustrations on the left-hand side, the drive shaft 12 having been displaced relative to the eccentric element 16 along the guide track 30. This increases the distance between the position 28 and the axis of rotation 18, and there is also an increase in the overall movement which is caused by the drive shafts 12 rotating about the axes of rotation 18.

LIST OF REFERENCE SIGNS

-   V Advancement direction -   1 Grinding machine -   2 Abrasive holder -   4 Abrasive -   6 Workpiece -   8 Machine frame -   10 Motor -   12 Drive shaft -   14 Power-transmission element -   16 Eccentric element -   18 Axis of rotation -   20 Pressure-exerting element -   22 Movement mechanism -   24 Double arrow -   26 Surface -   28 Position -   30 Guide track -   32 Undercut -   34 Form-fitting element -   36 Fastening element 

1. A grinding machine for grinding a surface of a workpiece, comprising: at least one abrasive holder on which at least one abrasive is arranged; and at least one drive device for moving the at least one abrasive holder, wherein the at least one drive device has at least one drive shaft on which at least one eccentric element is arranged and which can be rotated about an axis of rotation, wherein the at least one eccentric element is arranged on the at least one abrasive holder at a distance from the axis of rotation, wherein the distance from the axis of rotation is adjustable.
 2. The grinding machine according to claim 1, wherein the at least one eccentric element is adjustable in length.
 3. The grinding machine according to claim 1, wherein the at least one eccentric element is arranged in a releasable manner on the at least one drive shaft and is arrangeable at different positions on the at least one drive shaft.
 4. The grinding machine according to claim 3, further comprising on the at least one eccentric element and on the at least one drive shaft mutually corresponding form-fitting elements which allow the at least one eccentric element to be arranged in a form-fitting manner on the at least one drive shaft.
 5. The grinding machine according to claim 4, wherein the mutually corresponding form-fitting elements have a guide track in or on which one of the mutually corresponding form-fitting elements is arranged in a displaceable manner.
 6. The grinding machine according to claim 5, wherein the one of the mutually corresponding form-fitting elements that is displaceable in or on the guide track is selectively clampable at different positions in or on the guide track.
 7. The grinding machine according to claim 1 wherein the at least one drive device has at least two drive shafts, and wherein an eccentric element is arranged on each of the at least two drive shafts.
 8. The grinding machine according to claim 1 further comprising at least one pressure-exerting element for subjecting at least part of the at least one abrasive to pressure, wherein the at least one pressure-exerting element is movable relative to the at least one abrasive.
 9. The grinding machine according to claim 8, wherein the at least one pressure-exerting element has a surface which has a structure.
 10. The grinding machine according to claim 9, wherein the surface of the at least one pressure-exerting element having the structure is directed toward the at least one abrasive. 